The present invention is directed to a system for the automatic actuation of a friction clutch arranged in the torque transmission path between engine and change-speed gearbox of a motor vehicle.
A system for the automatic actuation of a motor vehicle clutch is known from German Patent Application P 30 28 250.9. With this system the actuating element of the clutch is movable by a controllable drive device between a clutch release position, in which the clutch is disengaged irrespective of rotation rate, and a clutch engagement position in which the clutch is completely engaged. The position of the actuating element in the slipping range between a position of commencing torque transmission and the clutch engagement position is settable by a program control which responds to the engine rotation rate and controls the clutch engagement operation of the drive device according to a position characteristic provided by a function generator, as a function of the engine rotation rate. The clutch is disengaged when the shift lever of the change-speed gear is actuated for the initiation of the gear change or the engine rotation rate drops below a rotation rate value in the region of or below the idling rate. The function generator becomes effective in clutch engagement, especially during starting away, and engages the clutch in dependence upon the engine rotation rate, which rises in starting away.
The positioning characteristic suitably dimensioned for jerk-free clutch engagement in starting away, with which the function generator shifts the actuating element of the clutch, has proved to be in need of improvement in clutch engagement after gear change during driving of the vehicle. In some driving situations the clutch engagement does not take place without jerks.
It is the primary object of the present invention to improve the initially explained automatic clutch actuation system so that clutch engagement occurs smoothly, both in starting and in gear-changing during driving.